Noncircular lens positioning structure and its method

Abstract

A structure for positioning a plurality of noncircular lenses relative to a lens holding frame which holds the noncircular lenses precisely. The structure includes a first lens frame which holds a first noncircular lens, and a second lens frame which holds a second noncircular lens. A first coupling part of the first lens frame has a first connecting surface which is perpendicular to a centering axis of the first noncircular lens, and a second coupling part of the second lens frame has a second connecting surface, contacting with the first connecting surface, which is perpendicular to the centering axis of the first noncircular lens. When the first coupling part is connected to the second coupling part, they are prevented from rotating relative to each other around the centering axis which is perpendicular to both the first and second connecting surfaces, by a mechanism which prevents a mutual rotation between the first coupling part and the second coupling part of the lens frame.

What is claimed is: 
     
       1. A positioning structure comprising: a noncircular lens having a flat surface which is perpendicular to a centering axis of the noncircular lens and which is on a side of the noncircular lens and near a profile of the noncircular lens, and wherein the noncircular lens has a peripheral surface, a part of which is formed arcuate and parallel with the centering axis thereof and a part of which is formed flat and parallel with the centering axis thereof; and   a lens frame which holds the noncircular lens, wherein the lens frame has a first contact surface which contacts with the flat surface of the noncircular lens,   wherein the arcuate part of the peripheral surface is formed around the centering axis.   
     
     
       2. The positioning structure as claimed in claim 1, wherein the first contact surface of the lens frame is perpendicular to the centering axis of the noncircular lens. 
     
     
       3. The positioning structure as claimed in claim 1, wherein the flat surface of the noncircular lens is formed substantially symmetrical to a point with respect to the centering axis, and wherein the peripheral surface of the noncircular lens is formed substantially symmetrical to the point. 
     
     
       4. A positioning structure comprising: a noncircular lens having a flat surface perpendicular to a centering axis of the noncircular lens; and   a lens frame holding the noncircular lens, the lens frame having a first contact surface which contacts with the flat surface of the noncircular lens,   wherein the noncircular lens has a circumferential surface a part of which is formed arcuate and parallel with the centering axis, and the lens frame has a second contact surface which contacts with the circumferential surface of the noncircular lens, and wherein the arcuate part of the peripheral surface is formed around the centering axis.   
     
     
       5. The positioning structure as claimed in claim 2, wherein the noncircular lens has a planar surface which is on an opposite side of the circumferential surface, wherein the planar surface thereof is formed parallel to the centering axis, and wherein the lens frame has a third contact surface which contacts with the planar surface of the noncircular lens. 
     
     
       6. The positioning structure as claimed in claim 5, wherein a first part of the lens frame which has the second contact surface, and a second part of the lens frame which has the third contact surface, are made of separate members. 
     
     
       7. The positioning structure as claimed in claim 6, wherein the noncircular lens has a pair of vertical surfaces which are perpendicular to the planar surface thereof in which each vertical surface is parallel to the centering axis thereof, and wherein there is provided a third part of the lens frame which has a surface opposing the vertical surface of the noncircular lens in which the first part of the lens frame and the second part thereof are connected with each other by the third part of the lens frame. 
     
     
       8. The positioning structure as claimed in claim 6, wherein the first and second parts of the lens frame are directly connected to each other.